It is known in the prior art to use cage-like spacers made of titanium mesh in tube shapes between vertebrae to provide support to the cervical spine. Spacers are needed when either the vertebrae or disk are removed for pathological reasons due to injury or disease. One such spacer 10 is shown in FIGS. 6 and 7. Such prior art spacers are typically formed from a mesh 12 rolled into a tube extending longitudinally for the length of the removed vertebrae or disk. Rings 14 on both ends 16, 18 are intended to reinforce the mesh and maintain the desired diameter of the spacer and also connect to adjacent vertebrae with screws 20. Spacer 10 is filled with granular bone tissue which eventually fuse or graft together and with the healthy tissue above and below the spacer. The spacer maintains the granular bone tissue in place until the graft is complete. The prior art spacers are difficult to install between existing vertebrae and difficult to satisfactorily fill with such bone tissue. The corrugated ends 22 of the mesh often catch adjoining tissue as the spacer is being implanted between the desired vertebrae. The reinforcing rings 14 tend to collapse into the adjacent vertebrae and damage them, i.e., subsidence. The granular bone tissue placed within the mesh tends to fall out of the mesh during the positioning process, and the mesh makes it difficult to refill the spacer with additional bone tissue. Gaps between the bone tissue inside the cage often result, which cannot be readily detected or remedied. Consequently, the grafting process is slowed or results in a weakened graft or incomplete fusion and malalignment due to these gaps.
Consequently, a need exists for, and it is an object of this invention to provide, an improved cervical interbody device that is easier to install between cervical vertebral bodies and results in a stronger and more reliable graft.